Allan:

Rod and main bearings, check the crank for scores, regrind if necessary.

There amount of babbit on the MB bearings is amazing. You will probably have babbit stuck to the crank, but that's all, if the engine didn't lock up.

If it was still running and only knocks, pull it, flip it over, pull the crank, check it, and put new bearings in. Probably need to remove the rocker arms so that the valves won't hit, but you can remove the head too, if you want. No actually necessary.

Unless it also got seriously overheated (find out if you can), there will be no damage to anything else. Oil starvation will seize the camshaft, too, but not in a mile with no oil unless it was at 100 mph!

The 617 in the turbo W123 is the same engine.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!